In many structures electrical conduit or piping or the like is suspended from ceilings or beams. The conduit or piping or similar loads, hereinafter called the load, is held by supports which are suspended from the ceiling or from beams in the structure by threaded rods. The supports come in different forms. A trapeze support holds a number of loads side-by-side while a J support holds a single load. The supports are generally spaced about 8 to 12 feet apart depending on the weight, strength and other characteristics of the load and the architecture of the structure.
Earthquakes, wind and other factors sometimes cause buildings to sway and when buildings sway support systems and their supported loads oscillate both in the direction longitudinal to the axis of the load and in the direction transverse to that axis. To prevent oscillations hangers and supports have been braced against such movement by braces that are connected to the supports, extend from them at an angle and are connected to the overhead structure. Such bracing systems may prevent the hangers and supports from oscillating in any direction with respect to the supporting structure but they do not prevent the load itself from moving with respect to the structure when the structure is subjected to a swaying motion Thus, a supported pipe, for example, cannot move transverse to its long axis when the supporting structure sways but it can move longitudinally with respect to its support when the supporting structure sways in that direction.
A variety of devices have been used to prevent piping from sliding longitudinally with respect to a hanger but those devices are usually specifically designed for the characteristics of the load, a different one for each pipe size for example, and are also specifically designed for the characteristics of the hanger, for example a J hanger brace cannot be used with a trapeze hanger or a clevis hanger.